Java中的 Scanner close() 方法及示例

java.util.Scanner类的close()方法关闭已打开的扫描仪。如果扫描仪已经关闭，那么在调用此方法时，它将无效。

句法：

public void close()

返回值：该函数不返回任何值。

下面的程序说明了上述函数：

方案一：

// Java program to illustrate the
// close() method of Scanner class in Java
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            // Get the string
            String s = "Geeksforgeeks has Scanner Class Methods";
  
            // create a new scanner
            // with the specified String Object
            Scanner scanner = new Scanner(s);
  
            // print the next line of the string
            System.out.println("Scanner: "
                               + scanner.nextLine());
  
            // close the scanner
            scanner.close();
  
            System.out.println("\nScanner Closed.\n");
  
            System.out.println("Trying to use scanner"
                               + " after closing.");
  
            // print the next line of the string
            System.out.println(scanner.nextLine());
        }
  
        catch (Exception e) {
            System.out.println("Exception thrown:\n" + e);
        }
    }
}

输出：

Scanner: Geeksforgeeks has Scanner Class Methods

Scanner Closed.

Trying to use scanner after closing.
Exception thrown:
java.lang.IllegalStateException: Scanner closed

参考： https: Java/util/Scanner.html#close()